Effects of nanoadditives on stability of Pt/SnO2 as a sensing material for detection of CO

The effects of dopants and annealing temperature on the long term stability of SnO2-based gas sensors for detection of CO were investigated by doping Pt/SnO2 nanoparticles with MoO3, CeO2, Sm2O3 and SiO2. The sensing materials including pure SnO2 and SnO2 doped with 5.0 and 10.0 wt% of nanoadditives were synthesized by a sol-gel method, then they were impregnated with 1.0 wt% platinum. Accelerated stability tests were performed by exposing the fresh powders and the fabricated sensors to air with 30% relative humidity at 600 °C for 15 days. Gas sensing measurements to 100 ppm CO at 250 °C, were carried out on the fabricated sensors on the 5th, 9th, 12th and 15th days in addition to the fresh point. MoO3, CeO2 and SiO2 additives were found to be effective in stabilizing the performance of Pt/SnO2 sensor, while Sm2O3 did not have the same effect. Increasing the annealing temperature, in the synthesis process, led to a decrease in sensitivity decline during the exposure period.